Bipolar Power Supply Voltage Control for Neutral Wire Current
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Solution Overview
Problem
In bipolar power supply systems, the neutral wire current is not effectively controlled, leading to excessive currents that exceed cable specifications, affecting system reliability and energy yield, particularly in wind and photovoltaic systems where positive and negative voltage conversion apparatuses have different maximum output powers.
Innovation Solution
A controller adjusts the output voltages of the positive and negative voltage conversion apparatuses to maintain unchanged output power while controlling the neutral wire current within a preset range, using control units in each apparatus to increase or decrease voltage differences as needed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the neutral wire current is controlled by adjusting output power of positive and negative voltage conversion apparatus, then the neutral wire current can be reduced, but the power supply system cannot provide maximum output power
Solution Approach 1:
The patent changes the control parameter from output power to output voltage. By adjusting the output voltages of the positive and negative voltage conversion apparatus while keeping output power constant, the neutral wire current is controlled without sacrificing maximum output power capability.
Solution Approach 2:
The patent implements dynamic voltage adjustment where the controller continuously monitors and adjusts the output voltages of the voltage conversion apparatus in real-time to maintain optimal neutral wire current levels while preserving full output power capacity.
2Reliability
If the output power of positive and negative voltage conversion apparatus is limited, then the neutral wire current can be controlled, but energy yield is affected
Solution Approach 1:
The patent transitions from power-based control to voltage-based control, allowing the system to maintain full energy yield by adjusting voltages rather than limiting output power, thus eliminating unnecessary energy losses.
3Reliability
If the neutral wire current exceeds cable specification, then system reliability is affected, but adjusting output power reduces control flexibility
Solution Approach 1:
By changing the controlled parameter from power to voltage, the system gains enhanced adaptability and flexibility in controlling neutral wire current while maintaining system reliability and cable specification compliance.
Data Source
AI summary
A voltage conversion unit includes a positive voltage conversion apparatus and a negative voltage conversion apparatus. The inverter unit includes a positive inverter and a negative inverter. A negative output end of the positive voltage conversion apparatus and a positive output end of the negative voltage conversion apparatus are connected to a first end of a neutral wire, and a negative input end of the positive inverter and a positive input end of the negative inverter are connected to a second end of the neutral wire. When the neutral wire current does not meet the preset current range, the controller control the positive voltage conversion apparatus and the negative voltage conversion apparatus to change output voltages when output power remains unchanged, so that the neutral wire current meets the preset current range.